From my research, I'm seeing $100-$150/sqft depending on complexity and material.

Depending on how that goes, I’ll aim to repeat it 1 or 2 more times.

depending on where you are in NJ you might have the Lehigh Valley in PA a couple hours away, or Delaware, etc. you can go to meetups, see places in person, and start to build a network.

Adding this circuit in would likely be quite expensive depending on access between the laundry area and the panel.

Depending on what he is offering you i searched the address with the secretary of state. 

Going to depend much more on more details / your personal situation - all things equal you will probably get better rate/terms on conventional if you qualify for both

>The fact is there are more money and guests than ever in the STR worldi think this is very market dependent.  

It depends on what the terms of your mortgage are.Pros-with no mortgage, you have higher cash flow.Cons-if you plan on buying more properties, you are better off saving the money for a down payment for your next place.The big questions are: can you get higher than 7% return if you invest that money elsewhere? 

In our experience, things move in ebbs and flows and the speed of rental depends on your asking rents relative to competition.For example, there was a period of several months at one of our properties when a 3 or 4 BR unit came on the market it rented almost instantly. 

The market is always evolving and there may be good deals to be had near term or you may need to wait a while, depending on many factors like interest rates etc.